1. Field of the Invention
The present invention relates to methods of forming one or more fractures in a high temperature subterranean zone and consolidating proppant particles therein.
2. Description of the Prior Art
Hydrocarbon producing wells are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing, a viscous fracturing fluid which also functions as a carrier fluid is pumped into a subterranean zone to be fractured at a rate and pressure such that one or more fractures are formed in the zone. Proppant particles, e.g., graded sand, for propping the fractures open are suspended in the fracturing fluid so that the proppant particles are deposited in the fractures when the fracturing fluid is broken. That is, a viscosity breaker is included in the fracturing fluid whereby the fracturing fluid reverts to a thin fluid which is returned to the surface. The proppant particles deposited in the fractures function to prevent the fractures from closing so that conductive channels are formed through which produced hydrocarbons can readily flow.
In order to prevent the subsequent flow-back of the proppant particles as well as loose or incompetent fines with fluids produced from the subterranean zone, the proppant particles have heretofore been coated with a hardenable resin composition which is caused to harden and consolidate the proppant particles in the zone. However, when the subterranean zone has a temperature above about 375° F., the hardened resin composition and the permeable proppant particle packs consolidated therewith rapidly deteriorate which allows proppant particles and formation fines to flow-back with produced formation fluids. The flow-back of the proppant particles and formation fines is very detrimental in that it erodes metal goods, plugs piping and vessels and causes damage to valves, instruments and other production equipment.
Another problem encountered in the use of prior hardenable resin compositions for coating proppant particles is that the hardenable resin composition or components thereof have had short shelf lives. In addition, the hardenable resin composition components have heretofore had low flash points, i.e., flash points of about 60° F. or below, making them very dangerous to use. Also, when the prior hardenable resin compositions or components thereof have been stored at high ambient temperatures, the compositions or components have quickly hardened making them unsuitable for use.
Thus, there are needs for improved methods of consolidating proppant particles in subterranean fractures whereby the permeable packs of consolidated proppant particles formed are chemical and thermal degradation resistant at high temperatures, i.e., temperatures above about 375° F. Further, there are needs for improved hardenable resin compositions and/or the components thereof that have long shelf lives and high flash points.